This invention relates to a musical apparatus. More specifically, this invention relates to a player piano tracker bar and a method of making the tracker bar.
The use of tracker bars for player pianos is well known. Such tracker bars are disposed between two reels for the player piano paper tape. As the paper tape moves from one reel to the other, holes in the paper taper register (i.e., become in line with) holes in the tracker bar. Each hole in the tracker bar is connected by a hose to a pneumatic actuator, usually simply called a pneumatic. Upon the tracker bar sensing a hole in the paper tape, the pneumatic contracts and moves a bar attached to it, the bar in turn causing a piano key to move. Movement of the key will cause vibration of the string which corresponds to the sound of the piano.
Although tracker bars which have preciously been used have generally functioned as intended, most prior art designs have one or more of several disadvantages.
Prior art tracker bar designs are often quite difficult and/or time consuming to produce and/or assemble.
Prior art tracker bar constructions have often required the production of separate pieces or members for use with different models. For example, a tracker bar design adapted to mount to a spool frame by screw holes at the end of the tracker bar may not properly mount into an O-roll mounting. In order to produce models compatible with both spool frame mounting and the O-roll mounting (tracker bar ends have rectangular blocks, one of which accommodates a screw and the other of which fits into a mating rectangular slot) a manufacturer might be required to stock two different types of manifolds for the components of the tracker bars. The requirement to make separate pieces for the different types of mounting increases a manufacturer's cost, whereas the manufacture who limits his product to a particular type of mounting may limit the size of his available market.
A further disadvantage of numerous prior art tracker bar designs is that they may use screws and/or gaskets in assembling the tracker bar. The gaskets are used to seal off air passages to ensure proper control of the pneumatics by the tracker bar, whereas the scres may be used to hold pieces of the tracker bar together. This increases the number of parts required for assembly and mayr equire a very complex pattern for the gasket, thereby increasing the cost of production.
Some prior art tracker bar designs use glue or solder in such a way that the glue or solder may inadvertently clog or partially restrict air flow in passages.
A particular prior art transposing tracker bar 10 is shown in FIG. 1. The tracker bar 10 is "transposing" in that it includes first and second end segments 12F and 12S and middle segment 12M. The middle segment 12M is slidably mounted between the two end segments 12F and 12S so as to vary the key in which music is played. The end segments 12F and 12S are mounted by screw holes 14 such that the player piano paper tape (not shown) may move along in contact with the front (i.e., underside in the view of FIG. 1) of the segments 12F, 12M, and 12S. A thumbscrew 16 and metal rods including the visible rods 18 are used to vary the position of the middle segment 12M in between the two end segments thereby changing the key in which the music is played. Each of the segments 12F, 12M, and 12S include ridges 20 (labeled for segment 12M) which extend or project upwardly (i.e., upwardly in the view of FIG. 1) disposed between a central channel 22. Projecting upwardly from the channel 22 are a series of tubes 24. The tubes 24 are made of brass or other metal and are soldered or welded into the channel 22 to connect to one of a series of holes (not visible) which extend through to the paper tape side, (backside in the view of FIG. 1) of the tracker bar 10. The holes on the paper side of the tracker bar 10 are aligned in a single row for the middle setment 12M, this row corresponding to musical notes initiated by the paper tape as it moves in perpendicular direction to the length of the tracker bar 10. The holes on the paper side for segments 12F and 12S may be slightly widthwise offset from each other as the tubes 24 mounted upon the end segments 12F and 12S correspond to special effects controls. From the single line of note holes on the paper side of middle segment 12M, the tubes 24 obtain some widthwise offset. That is, the tubes 24 generally extend normal to the plane of view of FIG. 1 except that every other tube 24 on the middle segment 12M is inclined toward alternating ones of the ridges 20. In this fashion, hoses (not shown) may be connected to the tubes 24 to allow operation of the pneumatics from the tracker bar 10. Because of the need to weld or otherwise fix the tubes 24 in place one at a time, it is difficult, time consuming, and expensive to assemble the tracker bar 10. Further, the division of the tubes 24 into two rows is somewhat undesirable in that the pneumatics are usually arranged in three rows. Therefore, it is difficult to easily connect the hoses between the tubes 24 and pneumatics.
An alternate arrangement to that of FIG. 1 provides a non-transposing tracker bar wherein there is but a single segment. This alternate design uses a slightly greater number of tubes 24 as there is no gap between segments, but the length of the alternate tracker bar is the same as that shown in FIG. 1. Effectively, this alternate tracker bar design has a slightly longer middle segment 12M which is unitary with the end segments. No thumbscrew or metal rods 18 are necessary as this alternate non-transposing design does not include movable parts.
FIG. 2 shows an alternate prior art design for a base 30 of a tracker bar. The base 30, which is made of metal such as lead, has a front piece 32 disposed behind a back cover piece 34 in the back view of FIG. 2. Holes 36 are disposed at both ends of the base 30 in order to mount this tracker bar construction to a spool mount arrangement. The cover piece 34 includes a plurality of circular holes 38 (only some of which are labeled) which register with rectangular passages 40. The rectangular passages 40 each extend in a straight line to openings (not visible) on the front of the piece 32. Although the rectangular passages 40 are idsposed in 3 rows corresponding to the 3 rows of holes 38, it should be noted that the holes on the front of piece 32 would be disposed along a single line (with the possible exception of minor variations for passages and/or holes corresponding to special effects). Therefore, the rectangular passages 40 extend generally normal to the view of FIG. 2, but are sufficiently angularly offset from normal such that a row of the passages 40A open at holes on the front side of piece 32 which are disposed in line with the middle row 40B of passages. The middle row of passages 40B are oriented precisely normal to the view of FIG. 2, whereas the lower row of rectangular passages 40C are generally normal, but are angularly offset to mate with openings along 40B. By virtue of the angular offset of passages 40A and 40C relative to passages 40B, the passages may proceed from a common line disposed at the center of piece 32 and branch out to three seperate rows of openings. Disadvangeously, the base 30 must be attached by screws (not shown) extending into screw holes 42 to a manifold and gasket arrangement (not shown). The gasket ensures separate seals at the interface between the various holes 38 and numerous passages which are disposed in a wooden block screwed into the holes 42. The wooden block has 3 rows of tubes mounted to its top so as to allow the connection of hoses extending from the tubes to pneumatics. The necessity for a relatively complex gasket and the requirement for a large number of screws to hole the manifold against the base are undesirable features. Further, both the cover piece 34 and the front piece 32 are made of relatively heavy metal and are usually welded together.